A location based service (LBS) is used for acquiring geographical location information about a terminal device and providing relevant information services for a user according to the acquired geographical location information. When information services are provided, peripheral retrieval is a very important service. For example, various map applications (APPs) may provide peripheral point of interest (POI) information according the geographical location where a terminal device is located, thereby helping a user to use the terminal device to inquire about the locations of a restaurant, a cinema, common facilities, etc. within a predetermined range surrounding the location. As another example, in taxi paging software, the need to send a paging request to a terminal device in a taxi within a predetermined range based on a location where a user is located.
For the sake of the factors of inquiry efficiency and stability, the existing manner for calculating a reachable area widely uses a concentric circle or a rectangle as a reachable range of a user. That is to say, when services of peripheral retrieval, etc. are carried out, a concentric circle or a view display area serves as a result filtering condition. The existing practices actually assume that a user has various isotropic moving abilities as if on a uniform surface which is infinitely large; however, actually, a moving policy of the user is often moving along a road network, and the distance moved after leaving the road network will not be too far, and therefore, an actual reachable area of the user should be a buffer area of a path on which the user may extend. Another problem in the existing practices is not considering the influence of landforms which can not be crossed by a user, such as a closed area, a water area or a mountain, on the user reachable area; however, road network-based reachable area analysis may avoid similar problems to some extent.
However, the calculation efficiency of the existing method for calculating a reachable area based on a road network is not high, and the calculation cost is higher than that of the method for calculating a reachable area based on concentric circles or grids. Sample statistics in the Beijing area show that time spent on inquiries based on a road network of over 2.3 km may exceed 500 ms; therefore, the aspect of efficiency of the manner for calculating a reachable area based on a road network still needs to be improved.